Discrete Fourier analysis of ultrasound RF time series for detection of prostate cancer.

In this paper, we demonstrate that a set of six features extracted from the discrete Fourier transform of ultrasound Radio-Frequency (RF) time series can be used to detect prostate cancer with high sensitivity and specificity. Ultrasound RF time series refer to a series of echoes received from one spatial location of tissue while the imaging probe and the tissue are fixed in position. Our previous investigations have shown that at least one feature, fractal dimension, of these signals demonstrates strong correlation with the tissue microstructure. In the current paper, six new features that represent the frequency spectrum of the RF time series have been used, in conjunction with a neural network classification approach, to detect prostate cancer in regions of tissue as small as 0.03 cm2. Based on pathology results used as gold standard, we have acquired mean accuracy of 91%, mean sensitivity of 92% and mean specificity of 90% on seven human prostates.

Real-time sonography to estimate muscle thickness: comparison with MRI and CT.

PURPOSE: We investigated the feasibility of using real-time sonography to measure muscle thickness. Clinically, this technique would be used to measure the thickness of human muscles in which intramuscular microstimulators have been implanted to treat or prevent disuse atrophy. METHODS: Porcine muscles were implanted with microstimulators and imaged with sonography, MRI, and CT to assess image artifacts created by the microstimulators and to design protocols for image alignment between methods. Sonography and MRI were then used to image the deltoid and supraspinatus muscles of 6 healthy human subjects. RESULTS: Microstimulators could be imaged with all 3 methods, producing only small imaging artifacts. Muscle-thickness measurements agreed well between methods, particularly when external markers were used to precisely align the imaging planes. The correlation coefficients for sonographic and MRI measurements were 0.96 for the supraspinatus and 0.97 for the deltoid muscle. Repeated sonographic measurements had a low coefficient of variation: 2.3% for the supraspinatus and 3.1% for the deltoid muscle. CONCLUSIONS: Real-time sonography is a relatively simple and inexpensive method of accurately measuring muscle thickness as long as the operator adheres to a strict imaging protocol and avoids excessive pressure with the transducer.

Extended field-of-view sonography: utility in clinical practice.

The purpose of this study was to evaluate the usefulness of real-time extended field-of view sonography in clinical practice (i.e., the frequency of use in various body systems, the frequency of use by different sonographers, and the benefits and drawbacks in comparison to conventional real-time sonography). The use of extended field-of-view sonography was monitored for a 6 month period. The pattern of usage among different sonographers and for different body systems was documented. Extended field-of-view sonography was utilized in 26.5% of patients. In comparison, color Doppler sonography was used in 23.2% of patients. Utilization of extended field-of-view sonography varied significantly among sonographers and among different body systems. Extended field-of-view sonography allowed measurement of large structures and revealed the anatomic context of abnormalities in circumstances under which conventional real-time scans could not provide this information.

Antenatal hydronephrosis: thresholds of renal pelvic diameter to predict insignificant postnatal pelviectasis.

We tested the parameters of gestational age and renal pelvic anteroposterior (AP) diameter of antenatally detected pelvicaliectasis for their ability to determine insignificant postnatal renal pelvic dilatation. A retrospective analysis of 10,365 antenatal sonograms revealed 121 kidneys with pelvicaliectasis, from which 99 sonograms with sufficient postnatal follow-up were reviewed. Gestational ages were classified as <20, 20-30, or >30 weeks. Thresholds of renal pelvic AP diameter in each gestational period that were predictive of postnatal insignificance were determined to be <6, <8, and <10 mm, respectively. Insignificance postnatally was defined as no or minimal renal pelvic splitting (Society for Fetal Urology grade

The association between preterm newborn hypotension and hypoxemia and outcome during the first year.

Ninety-eight newborn infants, less than 34 weeks at birth, were studied to examine the relationship between newborn hypotension and hypoxemia and brain damage. Heart rate, blood pressure and oxygen tension were recorded continuously during the 96 h following delivery. Outcome measures included neuropathology in children who died, and motor and cognitive development at one year corrected age in children who survived. There were 22 children with a minor and 27 with a major abnormal outcome. There was a relationship between newborn hypotension, newborn hypoxemia and low birth weight, and a major abnormal outcome. The probability of a major abnormal outcome increased from 8% in newborns with no hypotension or hypoxemia, to 53% in children with both hypotension and hypoxemia. These findings support the contention that combinations of sustained newborn hypotension and hypoxemia are important factors in the development of brain damage, accounting for a major abnormal outcome.

Hypotension and hypoxemia in the preterm newborn during the four days following delivery identify infants at risk of echosonographically demonstrable cerebral lesions.

This prospective study of 130 preterm newborns at less than 34 weeks gestational age has examined the predictive value of abnormalities in continuously recorded newborn blood pressure, heart rate, and oxygen tension during the 4 d following delivery for echosonographically demonstrable cerebral lesions (EDCL) identified in the infant by six months corrected age. EDCL consisting of intraventricular hemorrhage, ventriculomegaly, or hyperechoic parenchymal lesions in the brain were identified in 44 preterm newborns (34%). The incidence of EDCL in preterm newborns with no hypotension or hypoxemia was 13%. The incidence of EDCL was significantly increased in preterm newborns with either hypotension or hypoxemia. The probability of EDCL exceeded 50% when the total exposure to either hypotension or hypoxemia during the 4 d exceeded 50 mmHg-hours, or when newborn hypotension and hypoxemia occurred concurrently. No relationship to hypertension, bradycardia, or tachycardia was detected. These findings indicate that hypotension and hypoxemia in the preterm newborn during the 4 d following delivery are useful risk markers of EDCL.

Blood pressure and heart rate of the preterm newborn following delivery.

Thirty-five preterm newborns were studied to determine the mean blood pressure and heart rate of preterm newborns less than 1500 gm and greater than or equal to 1500 gm at birth. Systemic blood pressure increased and heart rate decreased with increasing maturity at birth. Both systemic blood pressure and heart rate increased during the four days following delivery. The 95% prediction limits of stable preterm newborns less than 1500 gm and greater than or equal to 1500 gm at birth are useful criteria to define hypertension and hypotension, as well as tachycardia and bradycardia.

The association of fetal and newborn metabolic acidosis with severe periventricular leukomalacia in the preterm newborn.

One hundred twenty preterm newborns less than 34 weeks' gestational age have been studied prospectively to determine the frequency of fetal and newborn metabolic acidosis and to examine the relationship of metabolic acidosis to periventricular leukomalacia as demonstrated by serial newborn ultrasonographic examinations. Fetal metabolic acidosis, based on an umbilical artery buffer base less than 34 mmol/L at delivery, occurred in three cases (2%), one of which had evidence of periventricular leukomalacia. Newborn metabolic acidosis that is based on a buffer base less than 34 mmol/L during the 4 days after delivery occurred in 12 cases (10%), five of which had evidence of periventricular leukomalacia. There is a significant relationship between the degree and duration of newborn metabolic acidosis and the occurrence of periventricular leukomalacia. This study indicates that systemic metabolic acidosis is an important pathophysiologic marker of periventricular leukomalacia. Intrapartum fetal asphyxia with metabolic acidosis, although an infrequent occurrence in the preterm newborn, may account for a few cases of periventricular leukomalacia, while the more common newborn metabolic acidosis, when of sufficient degree and duration, carries a high risk of periventricular leukomalacia.

Duplication of the aortic ring. An artifact in echocardiography.

Duplication or widening of the aortic ring is commonly observed in echocardiography. This imaging artifact arises from refraction of a portion of the sound beam by an unossified costal cartilage in the anterior chest wall. When the cartilage is situated in line with the edge of the aortic ring or just lateral to it, the artifact is produced. Given the anatomy of the costal cartilages, chest wall, and heart, the amount of refraction is calculated and compared with the amount of refraction actually observed in scans. The degree of duplication or widening of the aortic ring depends directly on the curvature of the costal cartilage and the distance between the cartilage and the aortic ring.

Pseudotumor of the quadrate lobe in hepatic sonography: a sign of generalized fatty infiltration.

Sonograms of 43 patients demonstrated a focal area of decreased echogenicity in the medial segment of the left hepatic lobe (quadrate lobe). The shape ranged from ovoid to sheetlike, and the diameter ranged from 0.7 to 8.6 cm. The echogenicity of the right hepatic lobe was abnormally increased in 34 of 37 scans graded. In 20 patients with follow-up sonograms, 11 showed no change, six disappeared and three decreased in size. In 12 patients with unenhanced CT scans, 10 had decreased attenuation of the hepatic parenchyma and normal attenuation in the observed quadrate lobe focus. The hypoechoic focus in the quadrate lobe represents focal sparing in generalized fatty infiltration of the liver. When present, this focus represents a useful qualitative sign of generalized fatty infiltration in the rest of the liver.

Motor and cognitive development of infants with intraventricular hemorrhage, ventriculomegaly, or periventricular parenchymal lesions.

Two hundred twenty-six moderate- or high-risk newborn infants were studied to examine the relationship between ultrasound findings in the newborn period and at 6 months and motor and cognitive deficits at 1 year. A three-part classification of abnormal ultrasound findings was used to grade intraventricular hemorrhage, ventriculomegaly, and parenchymal lesions. Abnormal ultrasound findings were observed in 48 infants, of whom 21 had intraventricular hemorrhage, 18 persistent ventriculomegaly, and nine parenchymal lesions. The incidence of deficits was as follows: normal ultrasound examination, 20%; intraventricular hemorrhage, 33%; persistent ventriculomegaly, 67%; and parenchymal lesions, 89%. The present study indicates that serial ultrasound examinations are indicated in preterm newborn infants less than 1500 gm and in selected newborn infants at risk and greater than 1500 gm at birth. The three-part classification of abnormal ultrasound findings should be used because of the predictive significance of persistent ventriculomegaly and parenchymal lesions for motor and cognitive deficits at 1 year of age.

Placental abruption and subchorionic hemorrhage in the first half of pregnancy: US appearance and clinical outcome.

In 30 pregnant patients who experienced vaginal bleeding between 10 and 20 weeks gestation, subchorionic hematomas were demonstrated on ultrasound examination. In 18 patients (60%), the margin of the placenta was separated from the uterine wall. In 15 patients the outcome was favorable (full-term delivery of normal infant) and in 15 patients the outcome was unfavorable (seven preterm births, four stillbirths, three spontaneous abortions, one therapeutic abortion). The major prognostic factor related to pregnancy outcome was the volume of the hematoma and, to a lesser extent, the relative volume of the hematoma (volume of hematoma divided by volume of gestational sac). For a volume less than 60 ml, the outcome tended to be favorable, and for a relative volume less than 0.4, the outcome tended to be favorable.

Maternal, fetal, and newborn complications associated with newborn intracranial hemorrhage.

Two hundred twenty newborn infants with one or more fetal or newborn complications and 54 newborn infants without fetal or newborn complications were prospectively studied to assess the relationship between maternal, obstetric, fetal, and newborn complications and intracranial hemorrhage. Intracranial hemorrhage occurred in 47 newborn infants with fetal or newborn complications (21%) and in one infant with no fetal or newborn complications (2%). Maternal and obstetric complications, duration of labor, and mode of delivery were not associated with intracranial hemorrhage. Newborn immaturity at delivery is an important factor in the occurrence of intracranial hemorrhage. There is little evidence that fetal hypoxia is a contributing factor. Severe respiratory complications and major infections are newborn complications associated with intracranial hemorrhage.

The split image artifact in pelvic ultrasonography: the anatomy and physics.

Transverse ultrasound scans of the pelvis often demonstrate double images or an apparent widening of the structures deep to the bladder. The phenomenon occurs when the real-time transducer is placed on the midline of the abdominal wall. Most of the widening effect or split image is caused by refraction of sound at the interface between the abdominal wall muscle and the collection of fat deep to the muscle. Using Snell's Law, it is possible to calculate the amount of splitting for a given anatomic configuration. The phenomenon is most exaggerated when the object is furthest away from the transducer and when the curvature between muscle and fat is largest.

Serial brain sonography in two children with leukomalacia and cerebral palsy.

Two premature neonates were followed by brain sonograms from the time of birth to eight and nine months of age respectively, and by clinical assessment until two years and eighteen months of age respectively. In both children, the sonograms demonstrated evidence of bilateral periventricular leukomalacia (infarction) with very little associated intracranial hemorrhage. (CT scans were performed shortly after birth as well.) White matter infarction was seen as multiple tiny cysts adjacent to the lateral angles of the lateral ventricles. Both children have cerebral palsy (spastic quadriplegia).

Healing in the traumatized spleen: sonographic investigation.

In 16 patients with abdominal trauma, ultrasonic abnormalities of the spleen were demonstrated shortly after trauma (mean 3.7 days). Initial sonographic abnormalities included: splenic laceration in 3 cases, intrasplenic fluid (hematoma) in 4, splenic inhomogeneity (contusion) in 8, perisplenic fluid (subcapsular hematoma) in 11, intraperitoneal fluid in 10, and a left pleural effusion in 7. Follow-up sonograms showed that pleural effusions and intraperitoneal fluid collections disappeared quickly (2 and 4 weeks, respectively). However, intrasplenic hematomas and contusions usually resorbed over a period of months (up to a year). When followed to complete resolution, the spleen may become normal sonographically or there may be small linear foci of echogenic material, which probably represent scar tissue.

Delayed regression of huge theca lutein cysts monitored by serial sonograms and beta-HCG levels.

The important role of serum beta-human chorionic gonadotropin (beta-HCG) in detecting spread of trophoblastic disease following evacuation of a hydatidiform mole is well established (1,2). Although sonography is accepted as the primary imaging technique in the diagnosis of hydatidiform mole (3), only a few authors have described the post-evacuation appearances of the pelvis, in particular the regression of theca lutein cysts (4,5). We here report a patient in whom there was delayed regression of huge theca lutein cysts compared to the regression of the serum beta-HCG levels after evacuation of a benign non-recurring hydatidiform mole.